In todays Orchestras unless it's been on the Bass awhile the two most common types are the Latched/Chromatic Extension or the Fingered/E-latch only Extension. This is what I have seen either on TV or in person. The NY Phil is mixed but Bill Blossom has made some Extensions for his and other Basses. The Philly Orch has either Mechanical Exts of older installations or Chromatic/Latched Exts with only one exception and that's the asst. Princ. Neil Courtney who has a Fingered/E-latch on his attrib. d'Salo Bass.
The difference in price between the
Fingered and
Chromatic is about 40% from my experience. My advice is get one of the guys who makes both types to make you a Fingered Ext. with the possibility of adding the latches later.
Arnold, Jeff? Wanna steer this guy on the right direction?